|Lateral line system||
Network of sensory receptors located along the head and sides of fishes and amphibians. The system serves to detect movements and pressure changes in the surrounding water. The individual receptor, called a lateral line organ, or neuromast, consists of a cluster of innervated hairs surrounded by a jellylike projection (cupula) that bends in response to water movements. The neuromasts of most bony fishes are set in a series of interconnected depressions, forming a canal, with openings at intervals to the environment.
Source: Encyclopaedia Britannica 2002